Railway signaling system



y 1931- J. c. HOFFMAN ,8 6,

RAILWAY S IGNALING SYSTEM Filed April 7, 1930 2 Sheets-Sheet 1 mvswronC. h'on'MAnl. M is: a M

ATTORN EYS y 1931. J. c. HOFFMAN 1,806,291

RAILWAY S IGNALI NG SYSTEM Filed April 1930 2 Sheets-Sheet 2 i K! L! T IF4 I r 0 E 2' E k.

I INVENTOR m JAY c Hoffman N M K W W ATTORNEY5 Patented May 19, 1931 1UNITED STATES PATENTOFFICE JAY C. HOFFBTAN, OF AKRON, OHIO BAILVVAYSIGNALING SYSTEM Application filed April 7, 1930. Serial No. 442,100.

My invention relates to railway signaling charged. Also the additionalresistance systems, especially an automatic electric placed in serieswith the magnet coils makes block-signal system using direct current andthe relay exceptionally sensitive and will dea normally closed trackcircuit. in such energize it instantly when the track circuit systemsthe automatic operation of the track is occupied by a train, a veryessential feag circuit in each block is effected by changes ture onrailroads operating trains at a high in weather conditions or theseasons, and a rate of speed. customary practice is to have inspectorsand In the accompanying drawings, Figs. 1 and repairmen adjust thecurrent How in the 2 are side and front elevations, respectively, 3 9track circuits prior to wet and dry weather partly in section, of arelay constructed to seasons so that the system may function carry outmy conception, and invention. efl'ectively during each season. Thusduring Figs. 3 and 4 and 5 are diagrams of a section wet weather periodsa considerable amount or block of a railway signaling system havofelectric current leaks from rail to rail ing such a relay in circuittherewith, and A through the wet ballast and cross ties, and showing theoperation thereof under difiera greater amount of energy or current isrecnt conditions. qmred at this time to Operate the track cir- The relayA shown in Figs. 1 and 2 is cuit than in dry weather. Accordingly, thein some respects similar to the relays ordicurrent flow in the trackcircuit must be regnarily used for the same purpose in that it ulated,otherwise under one condition the embodies a pair of magnet windings orcoils track relays become less sensitive in response 2 and 3, and a pairof pole pieces 4 and 5, to a train shunt, and under anothercondirespectively, mounted on a suitable box or tion there is danger ofthe relay remaining base 6 carrying any desired or required numenergizedand producing a false signal indiber of binding posts 7 to permit thedevice cation. However. manual supervision and to be connectedelectrically to a railway sigregulation has its objections andlimitations. naling system. The relay also includes a and my object ingeneral is to provide automain armature 8 hinged opposite the ends maticmeans for regulating the current flow oi the pole pieces, which armaturecarries in the track circuits so that the system will one or morecircuit make and break devices.

d operate efficiently and safely at all times such as an arm 9 having aspring Contact under all weather conditions. In carrying member 10adapted to make and break conout my object I provide means which willtact with a. pair of terminal members 11 and automatically cut in aresistance in series 12, respectively, connected to a pair of the with anormally-closed track circuit when binding posts.

135 the current flow therein reaches a predcter- Now the features whichdistinguish relay mined value, thereby maintaining or increas- *A* fromothers known to me reside mainly ing the sensitiveness of the circuit toa train in the coupling of a resistance element or coil or car shunt. Ahigher degree of broken B in series with the magnet coils 2 and 3. railprotection is also thereby provided, and respectively, either one orboth of them, and.

" the electrical energy consumption in the in the use oi an auxiliaryarmature C adjatrack circuit is considerably reduced comcent the polepieces 4 and 5. respectively, topared with prior practices. Preferably.gother with a suitable circuit make and break employ a self-regulatingrelay which includes device I) operated by the auxiliary armaa. pair ofmagnet coils and an auxiliary ture, whereby when the current flowthrough armature, and interpose the desired resistthe magnet coilsreaches a predetermined ance between the magnet coils in this relay.amount or value, the auxiliary arn'iature will In action, the resistancewill be cut in auto be attracted and the resistance element B matieallyin series, with the magnet coils will be cut in or placed in circuit inser es when the energy applied reaches a value with either one or bothof the magnet coils which will not cause the magnets to be overof therelay.

As shown, the auxiliary armature C is pivotally supported upon a bracket14 at one side of the pole pieces 4 and 5 but with a larger air gap orat a greater distance therefrom than main armature 8. Accordingly, themain armature will be attracted initially when current flows through themagnet coils, and a small amount of current will hold the main armatureattracted, whereas the auxiliary armature will not function until aredetermined higher amount of current ows through the relay magnetcoils. The auxiliary armature can also be set or adjusted by a set screw15, and by a change in tension of its controlling spring 16, to cause itto operate at any point within the range of the energy or current flowcommonly used in a normally-closed railway signaling track cir cuit,represented in Figs. 3 to 5, by a section or block of tracks E having asource of electric current such as a battery F connected therewith,including an adjustable resistance The make and break device D is shownin Fig. 1 as comprising a contact spring 17 normally engaged with afixed contact blade 18 and adapted to be raised apart therefrom by anarm 19 extending from armature C when this armature is attracted by thepole pieces. An adjustable weight 20 may also be con nected to arm 19 tocontrol the action of auxiliary armature C. The contact member 17 andpiece 18 are connected to binding screws 2222 which are attached toupright supporting conductors 23-23 for the resistance element or unitB, and this resistance unit is connected in series with the magnet coils2 and 3 of the relay but shunted or cutout from the track circuit E whenthe switch contacts 17 and 18 are engaged.

Track circuit E is a normally-closed circuit, and self-regulating relayA is connected therein at. one end of the section or block of tracks ascustomarily, while the battery F and adjustable resistance G areconnected to the opposite end of the tracks in the same section orblock. In practice, the adjustable resistance G is set to permit aminimum amount of current to flow from the battery to maintain the trackcircuit and to attract and hold main armature 8 when the ballast andcross ties are wet, but without operating the auxiliary armature.Accordingly, resistance B is cut out at this time, or when he currentlosses are at maximum. Regulation or due allowance having been made forcurrent losses. the track circuit is then adapted to function with aconsiderable degree of safety during wet weather periods. However, whenwet weather conditions are succeeded by a dry or cold period, and nosuch losses of current occur, the relay magnet coils become overchargedwith current to such an extent that the relay is less sensitive orresponsive to a train shunt, and the train shunt or short-circuiting ofthe track circuit by the car wheels is also less effective or not aseasily effected in dry weather. Thus when the relay is overcharged thereis a much smaller margin of safety in dry or cold weather and moredanger or risk that a false signal will be given.

The automatic regulating relay A, increases the margin of safety in suchtrack circuits as it corrects or compensates for the differences incurrent flow in the track circuit under the varying conditions whichprevail, and permits the track circuit to perform equally as well in dryor cold weather as in wet weather. Thus, in wet weather the auxiliaryarmature is normally released which cuts out the resistance C as shownin Fig. 4 to permit the relay to function sensitively with a minimumamount of current at a time when leakage and losses in current are moreprevalent. In dry weather when leakage is less or no loss of currentoccurs the auxiliary armature is attracted to place the re sistance B inseries with the relay coils as shown in Fig. 3, whereby the relay isprevented from overcharging and again maintained in a sensitive andresponsive state to a train shunt or short circuit. Fig. 5 shows awheeled truck or car H in the track block and in this case the trackcircuitis shortcircuited and relay A is completely dc-energized toproduce a signal over any suitable signaling circuit or circuits J. Thesignaling circuit is only shown in part, inasmuch as such circuits arewell known and used in many ways, singly or in multiple.

In operating a track circuit embodying the present invention theelectrical energy or current consumed is considerably reduced ascompared with gmicral pinctice-s: the relay functions with increasedsensitivity and responsiveness; the margin of safety is increased; therelay operates reliably under a train shunt produced by either light orheavy railway traveling equipment; and freqlruent periodical resistanceadjustments in t e battery current supply may be avoided.

VVh-at I claim is:

1. Ina railway signaling system, a normally closed track circuit havinga source of current supply, a signaling circuit, a relay in said trackcircuit, a main armature, for said relay controlling said signalingcircuit. and an auxiliary armature for said relay operated by thecurrent flowing through said track circuit and dimensioned to beactuated under different current values than said main armature forproducing additional resistance in said track circuit automatically whenthe current values exceed a predetermined settin 2. In a railwaysignaling system. a normally-closed track circuit, a source of electriccurrent, means for regulating the amount of Current supplied to saidcircuit, a signaling circuit, a relay in said track circuit forcontrolling said signaling circuit, a resistance in series with saidrelay, and automatic means controlled by said relay for short-circuitingsaid resistance under predetermined settings of said current regulatingmeans.

3. In a railway signaling system, a circuit containing a relay andresistance in series; said relay having a main armature and switchingdevices for controlling a signaling circuit, and an auxiliary armatureand switching means for short-circuiting said resistance.

4. In a railway signaling system, a normally-closed track circuit, meansfor regulating the amount of electric current for said circuit, a signalcontrolling relay connected with said circuit, and automatic meanscontrolled by said relay for maintaining said relay sensitivelyresponsive to a train shunt in said circuit under changes in potentialinduced by different Weather conditions.

5. In a railway signaling system, a circuit, a relay having a pair ofmagnet coils connected in said circuit, a resistance element, and meansfor cutting in said resistance element in series and between said magnetcoils when the electric energy applied to same exceeds a predeterminedvalue.

6. In a railway signaling system, a direct current relay having anarmature, magnet coils and a resistance element adapted to be connectedin series relation, and make and break devices operatively controlled bysaid armature for placing said coils and resistance element in seriesrelation When the electric energy flowing through said coils reaches apredetermined value.

7. In a railway signaling system, a relay having a main armature, andmeans for making and breaking a signaling circuit, including anauxiliary armature less responsive than said main arn'iature, magnetcoils and a resistance element adapted to be connected in an electriccircuit, and means operativcly controlled by the movement of saidauxiliary armature for cutting said resistance element in and out ofsaid circuit.

In testimony whereof I aifix my signature.

JAY G. HOFFMAN.

